At times you need a way to send and receive SOAP headers in your message - these headers may not be defined in the WSDL binding but your application needs to do it anyway. One approach has been to write a SOAPHandler to do it, but its more work and is expensive as SOAPHandlers work on SOAPMesssage which is DOM based and JAX-WS runtime would need to do conversion from its abstract Message representation to SOAPMessage and vice versa.

There is a way to do it on the client side by downcasting the proxy to WSBindingProvider and use methods on it.

HelloService helloService = new HelloService();
HelloPort port = helloService.getHelloPort();
WSBindingProvider bp = (WSBindingProvider) port;

bp.setOutboundHeaders(
        // simple string value as a header, like stringValue
        Headers.create(new QName("simpleHeader"), "stringValue"),
        // create a header from JAXB object
        Headers.create(jaxbContext, myJaxbObject));

List<Header> inboundHeaders = bp.getInboundHeaders();

Web Services developers generally need to see SOAP Messages that are transferred between client and service for debugging. There are SOAP Monitors for this job, but you need modify the client or server code to use those tools. JAX-WS RI provides logging of SOAP messages

com.sun.xml.ws.transport.http.client.HttpTransportPipe.dump=true

com.sun.xml.ws.transport.http.HttpAdapter.dump=true

This is a very useful feature while developing Web Services. Often the soap fault messages for not user defined faults does not convey enough information about the problem. JAX-WS RI relieves you from digging out the server logs to find out the stacktrace. Whole stacktrace (including nested exceptions) can be propagated in the SOAP Fault and the complete exception stacktrace can be made visible to the client as cause of SOAPFaultException.

com.sun.xml.ws.fault.SOAPFaultBuilder.captureStackTrace=true